Fix AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’ for Beginners – NumpPy Tutorial

By | April 13, 2020

If you plan to insert a value to the end of a numpy.ndarray, you will get an error: AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’. In this tutorial, we will introduce how to fix this error.

Here is an example:

import numpy as np

data = np.array([1,2,3])
data.append(4)

Run this code, you will get the result:

fix AttributeError 'numpy.ndarray' object has no attribute 'append'

Why does this attribute error occur?

Because there is no numpy.ndarray.append() funtion in numpy.ndarray.

How to fix this error?

We can use numpy.append() function.

numpy.append(arr, values, axis=None)

This function will append values to the end of an array.

As to example above, we can modify it to be:

import numpy as np

data = np.array([1,2,3])
datax = np.append(data, 4)
print(data)
print(datax)

Run this code, you will get the result as:

[1 2 3]
[1 2 3 4]

From the result we can find: The original numpy.ndarray data is not changed, numpy.append() function will return a new numpy.ndarray.

You will find this error is fixed.

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